Borescope light



E. B. CHILDS BORESCOPE LIGHT Dec. 14, 1965 2 Sheets-Sheet 1 Filed May 31, 1962 Dec. 14, 1965 E. B. CHILDS 3,223,832

BORESCOPE LIGHT 2 Sheets-Sheet 2 Filed May 31, 1962 m ,0 32 25 W .L i 54 T United States Patent Ofilice 3,223,832 Patented Dec. 14, 1965 3,223,832 BORESCOPE LIGHT Elbert B. Childs, Hastings on Hudson, N.Y., assignor to Socony Mobil Oil Company, Inc., a corporation of New York Filed May 31, 1962, Ser. No. 199,067 6 Claims. (Cl. 240-218) The present invention relates to borescopes, and more pagticularly to a power supply for energizing a borescope ig t.

A borescope is similar to a periscope with a light on the end thereof to enable the human eye to see into dark cavities devoid of other light. Instruments of this type are used by physicians and surgeons to inspect body cavities for pathological conditions, and other types of borescopes are used industrially to inspect gun barrels, boiler tubes, and parts in atomic power plants.

In accordance with the present invention, it has been found that borescopes can be advantageously utilized to inspect cavities or enclosed parts of combustion engines, gear cases, and the like, by inserting the borescope through a spark plug, injector or drain plug hole. Under ideal conditions, very clear images of the different parts can be seen, despite the fact that the light in the end of the boresocpe must necessarily be made small to pass through the 'sprak plug, injector or drain plug hole. However, when inspecting the condition of engine parts such as valve heads, cylinder walls and piston crowns in diesel engine combustion chambers, it is difficult to obtain clear images because the parts are black and sooty. Another difficulty often encountered in connection with inspecting gasoline engines is that the arrangement of some engine parts relative to the access hole produces shadows which cover important parts such as valve fillets.

It is one object of the invention to provide an improved borescope for internally inspecting combustion engines.

It is another object of the invention to provide an improved power supply for a borescope which increases the brightness of the borescope light without increasing the size of the light.

It is a further object of the invention to provide an improved power supply for the light on the end of a borescope which enables the light to be operated at a carefully controlled overvoltage to increase the brightness of the light several times without increasing its size.

It is a still further object of the invention to provide a power supply for the light of a borescope which enables the light to be momentarily subjected to extreme overvoltages for operation as a photoflash without destroying the bulb so that photographs can be taken of the cavity being inspected by the borescope.

It is a still further object of the invention to provide power supplies for operating the light of a borescope with either A.C. or DC. sources in a manner to increase the brightness of the light.

It is a still further object of the invention to improve the illumination of a cavity being examined by slidably and rotatably mounting a light carrier as a separate unit on a borescope to enable the light carrier to be positioned independently of the borescope to provide the best illumination of the area of the cavity being examined.

Other objects and features of novelty of the present invention will be specifically pointed out or will otherwise become apparent when referring, for a better understanding of the invention, to the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a longitudinal, broken, sectional view of a borescope embodying features of the invention;

FIG. 2 is a schematic diagram of a DC. power supply circuit for a borescope embodying other features of the invention;

FIG. 3 is a schematic diagram of a photofiash circuit for operating the light source of a boresocpe as a flash bulb;

FIG. 4 is a schematic diagram of an A.C. power supply for a borescope;

FIG. 5 is a fragmentary sectional view of the objective end of a borescope illustrating another embodiment of the invention;

FIG. 6 is a fragmentary sectional view similar to that of FIG. 5 illustrating still another modification of the invention;

FIG. 7 is a fragmentary sectional view similar to that of FIG. 5 illustrating still another modification of the invention; and

FIG. 8 is a fragmentary sectional view similar to that of FIG. 5 illustrating still another modification of the invention.

Referring to FIG. 1, a borescope 10 embodying features of the present invention is illustrate-d which comprises a borescope tube 13 having an ocular end 14 on one thereof and an inspection lens 16 on the other end thereof, which is referred to as the objective end. Suitable lenses 18 are also mounted in the borescope tube intermediate the ends thereof and a correcting prism 19 is mounted in the ocular end 14 in a conventional fashion.

A light carrier 20 is slidably and rotatably mounted on the borescope tube 13 and comprises a tube 22 having a socket base 24 on the end thereof adjacent to the ocular end 14 of the borescope tube and a light bulb socket 26 on the other end thereof adjacent to the objective end of the borescope tube. A suitable light bulb 28 is carried in the socket 26 and the lower portion of the light tube 22 is cut away as at 30 to provide a field of view for the inspection lens 16. The light bulb 28 is energized by current supplied through conductors 32 and 34 extending from an outlet 36 on the side of the socket base 24. The conductor 34 extends through the socket base and along the outer wall of the light tube 22 to the light bulb socket 26 and the circuit for the light bulb is completed through the light tube and the conductor 32 connected thereto. With this construction, the objective end of the borescope 10 can be introduced into the combustion chamber of a gasoline engine through one of the spark plug holes, for example, to inspect the inside of the combustion chamber, and the light carrier 20 can be adjusted axially and rotated relative to the borescope tube 13 to position the light bulb 28 with respect to the inspection lens 16 to eliminate shadows and provide the best illumination and view of the combustion chamber.

In using borescopes with diesel and gasoline engines, the injector and spark plug openings through which the borescope must be introduced are often as small as of an inch in diameter. Consequently, the borescopes must be small in size and the light bulbs used in connection with the borescopes must be correspondingly small. A typical light bulb commonly used with such borescopes is rated at six volts. In accordance with the present invention, the light provided by such small bulbs is significantly increased by providing a power supply for operating the bulb at a considerable, but carefully controlled, overvoltage to increase the brightness of the bulbs up to six times. An example of such a power supply which can be connected directly to the twelve volt battery of an automotive vehicle, if desired, is illustrated in FIG. 2. It comprises a pair of terminals 40 which are adapted to be connected directly to the vehicle battery (not shown) vwith a second pair of terminals 42 connected to the conductors 32 and 34 projecting from the outlet 36 of the light carrier 20. A D.C. voltmeter 44 is connected across the terminals 42 to indicate the voltage thereacross and a double-pole double-throw reversing switch 46 is prefera-bly provided to control the direction of current passing through the voltmeter. A rheostat 48 is provided as shown to adjust the voltage across the terminals 42 and a fixed resistor 59 may also be provided which can be connected in series with the rheostat by a single-pole double-throw switch 52 to vary the range of the voltmeter 44. If desired, an internal battery 54 may be connected in parallel with the voltmeter along with a single-pole double-throw switch 56 to provide an alternative source of power in the event a vehicle battery is not available. When the switch 56 is in the position illustrated in FIG. 2 the vehicle battery (not shown) provides the power and when the switch 56 is shifted to engage a contact 58, the internal battery 54 provides the power.

In the preferred embodiment, the light bulb of the borescope which is energized by the power supply illustrated in FIG. 2 is a six volt bulb but is operated at a substantially higher voltage of approximately twelve volts which is carefully controlled by the rheostat 48 to maintain the voltmeter 44 at a constant reading. In this preferred embodiment, the voltmeter has a range of O-lS volts, the rheostat 48 has a maximum resistance of fifty ohms and the internal battery 54 is a twelve volt battery to provide the power in the event a twelve volt vehicle battery is not available. The resistor which is cut in or out of the circuit by the single-pole double-throw switch 52 to change the range of the voltmeter 44 is preferably a fifty ohm resistor. A fuse 60 is also provided in the circuit and in the preferred embodiment is a one-amp fuse.

In accordance with the present invention, a photofiash circuit is also provided for momentarily subjecting the light bulb 28 to an extreme overvoltage so that it operates as a photofiash with the exception that it is not destroyed in the process. This enables photographs to be taken of the interior of a combustion chamber by photographic equipment positioned adjacent to the ocular end 14 of the borescope. A suitable photofiash circuit is illustrated in FIG. 3 and comprises a capacitor 66 connected in parallel with a battery 68 and a pair of terminals 70 adapted to be connected to terminals 72 which are shown in FIG. 2 and connected directly to the terminals 42 when a single-pole double-throw switch 74 is shifted from the position illustrated in FIG. 2 into engagement with a con tact 76 connected directly to one of the terminals 72. The photofiash circuit also has a fixed resistor 78 normally connected in series with the capacitor and battery by a single-pole double-throw switch 80 and an auxiliary resistor 82 adapted to be added in series with the resistor 78 when the switch 80 is shifted into engagement with the contact 84. To complete the photofiash circuit a singlepole double-throw switch 86 is connected in series with the battery 68 and a single-pole single-throw switch 88 is connected in series with the resistor 78. Both of the switches 86 and 88 are normally open and of the type which close momentarily and quickly reopen when actuated. With this arrangement the switch 86 can be actuated to place a predetermined charge on the capacitor 66 and the switch 88 can be actuated thereafter to flash the light bulb. If the light bulb 28 is the six volt bulb mentioned previously, the preferred embodiment of the photofiash circuit would employ a twenty-two and one-half volt battery 68, a four thousand mf. sixty volt capacitor 66, a two ohm, five watt resistor 78 and a twelve ohm, five watt resistor 82.

If it is desired to operate the light bulb of the borescope on AC. current, the AC. power supply illustrated in FIG. 4 may be employed. This power supply comprises a pair of terminals 90 adapted to be connected to the AC. power source, such as for example a 117 volt, 60 cycle source which is fed to a transformer 92 for stepping the voltage down to twelve volts. A single-pole single-throw switch 94 is provided in the circuit to the transformer along with a fuse 96 which, in the preferred embodiment, is a one-half amp fuse. A second pair of terminals 98 are connected to the lines 32 and 34 to energize the light bulb as previously described, and an AC. voltmeter 100 having a 0-15 volt range is connected across the terminals 98. A rheostat 102 is connected in series with the voltmeter along with a fixed resistor 104 which is added in series with the rheostat 102 when a single-pole double-throw switch 106 is shifted into engagement with a contact 108 on the end of the resistor 104. In the preferred embodiment, the rheostat has a maximum valve of fifteen ohms, and the fixed resistor 104 is also a fifteen ohm resistor.

Although in the embodiment of the borescope 10 illustrated in FIG. 1 the light bulb 28 is positioned beneath and extends downwardly from the inspection lens 16 on the objective end of the borescope, other arrangements may be utilized as shown in FIGS. 58 to provide a variety of positions between the light bulb and the objective end of the borescope to examine different types of cavities. In FIG. 5 the inspection lens on the objective end of the borescope projects beyond the light tube 22 so that the light bulb 28 is positioned above and projects toward the objective end. As before, the light tube can be shifted axially and rotated relative to the borescope tube 13 to provide the best position for illuminating the parts to be viewed.

In FIG. 6 the arrangement is the same as that in FIG. 5 with the exception that the position of the light bulb 28 is reversed so that it extends away from the objective end of the borescope rather than toward the lens as in FIG. 5. In the arrangement of FIG. 7, two light bulbs 23 are mounted on the light tube 22 above the objective end. The construction in FIG. 8 is identical to the construction shown in FIG. 1 wherein the light bulb 28 is positioned below and extends away from the objective end of the borescope. However, in this embodiment a mirror 110 is supported on an extension 112 of the light tube 22 adjacent to the end of the light bulb 28 to reflect the light in a desired direction.

While it will be apparent that the embodiments of the invention herein disclosed are well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

I. In combination an elongated tubular borescope having an eyepiece adjacent to one end thereof and an inspection lens and light bulb means adjacent to the other end thereof, said light bulb means having a voltage rating in the order of six volts and providing the sole light for enabling the inside of a cavity to be viewed through said eyepiece, and power supply means electrically connected to said light bulb means for applying a controlled continuous overvoltage to said light bulb means, said power supply means including variable means connected to said light bulb means for varying the voltage applied thereto, and voltmeter means connected to said variable means for indicating the voltage being applied to said light bulb means.

2. The combination as defined in claim 1 wherein said power supply means is a D.C. power supply means and includes terminal means for connecting the power supply means to a vehicle battery.

3. The combination as defined in claim 2 wherein said D.C. power supply means includes an internal battery connected in parallel with said terminal means, and switch means for selectively connecting or disconnecting said internal battery from said power supply means, said internal battery having a higher voltage rating than the voltage rating of said light bulb means.

4. The combination as defined in claim 1 wherein said power supply means is a D.C. power supply means comprising terminal means for connecting the power supply means to a vehicle battery, said voltmeter connected in parallel with said terminal means and light bulb means, an internal battery connected in parallel with said terminal means and light bulb means, switch means for selectively connecting and disconnecting said internal battery from said power supply means, said internal battery having a voltage rating greater than the voltage rating of said light bulb means, and variable resistor means for controlling the voltage supplied to said light bulb means by either of said batteries whereby the brightness of the light provided by said light bulb means can be increased considerably without increasing in size.

5. The combination as recited in claim 1 including photoflash means for momentarily operating said light bulb means at an extreme overvoltage without destroying the light, and switch means for electrically connecting said photoflash means to said light bulb means momentarily when actuated to subject said light to said extreme overvoltage.

6. The combination as defined in claim 1 further com prising means for mounting said light bulb means on said borescope adjacent to said other end for rotary and axial movement relative thereto whereby said light bulb means and inspection lens can be rotated and moved axially relative to one another to minimize shadows seen in the cavity through the eyepiece.

References Cited by the Examiner UNITED STATES PATENTS 1,088,695 3/1914 Goldensky et al. 315-291 X 1,163,887 12/1915 Burgess 240-1061 1,511,495 10/1924 Belden 315-291 X 1,844,790 2/1932 Norviel et al 315-77 X 1,969,459 8/1934 Fuller 315-291 2,290,264 7/ 1942 Wuerfel 315-241 2,410,369 10/ 1946 Sziklai 315-86 2,609,523 6/1951 Stein et al. -11.5 2,633,783 4/1953 Laval 95-11 2,856,562 10/1958 Grimm 315-241 2,858,416 10/1958 Hover 240-218 2,949,071 8/1960 Foures 128-6 2,959,089 11/1960 Hett 240-218 X 2,969,721 1/1961 Casselman et al. 315-241 X NORTON ANSHER, Primary Examiner. 

1. IN COMBINATION AN ELONGATED TUBULAR BORESCOPE HAVING AN EYEPIECE ADJACENT TO ONE END THEREOF AND AN INSPECTION LENS AND LIGHT BULB MEANS ADJACENT TO THE OTHER END THEREOF, SAID LIGHT BULB MEANS HAVING A VOLTAGE RATING IN THE ORDER OF SIX VOLTS AND PROVIDING THE SOLE LIGHT FOR ENABLING THE INSIDE OF A CAVITY TO BE VIEWED THROUGH SAID EYEPIECE, AND POWER SUPPLY MEANS ELECTRICALLY CONNECTED ON SAID LIGHT BULB MEANS FOR APPLYING A CONTROLLED CONTINUOUS OVERVOLTAGE TO SAID LIGHT BULB MEANS, SAID POWER SUPPLY MEANS INCLUDING VARIABLE MEANS CONNECTED TO SAID LIGHT BULB MEANS FOR VARYING THE VOLTAGE APPLIED THERETO, AND VOLTMETER MEANS CONNECTED TO SAID VARIABLE MEANS FOR INDICATING THE VOLTAGE BEING APPLIED TO SAID LIGHT BULB MEANS. 